MeganeAutomaticTransmission[1]

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307 Technology

This page last updated 12 April 2003.

Below I have discussed some of the technologies present in thePeugeot 307.

Multiplexing

The 307 utilises the latest Multiplex technology, developed inconjunction with PSA partner Citroen, Bosch and Renault. PSA firsttrialled this system back in 1994 on the Citroen XM.

With all the features now available in modern cars, the amount ofwiring required has become enormous. Electrical connections havegone up from around 200 to over 1000 in a modern car, resulting in aspaghetti like mess around the car. Instead of so many wires, amultiplexed system of 4 BUSes (containing 4 wires each) is used.These BUSes provide electric power to the various components aroundthe car, as well as sending individual digitally encoded messages foreach component. The car has 18 microprocessors.

The system is comprised of two networks, the faster 250kbps CAN(controller area network) and the slower VAN (vehicle area network),

which are bridged by the BSI/ISB (built in systems interface/intelligentservice box). BSI stands for Botier de Servitude Intelligent.

CAN was developed by Bosch, and controls the mechanical systems ofthe car, such as braking, ESP, engine management, the automaticgearbox, etc. VAN was developed by PSA and Renault, and iscomprised of three subnetworks - the safety BUS, body BUS andcomfort BUS - the elements of which are shown in the diagram below.


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The network can actually become congested, however, the systemgives safety commands priority over comfort commands.Understandably, in a car with a drive by wire throttle, you wouldn'twant the car to hesistate, waiting for some capacity in the network,when overtaking a large track on the other side of the road!

The benefits of this system are that more advanced systems can beadded. For manufacturers that limit their computer systems to theirown authorised dealer networks, car owners cannot service their carsat local garages, except for simple physical tasks. For authoriseddealers, diagnosing problems becomes much faster, as a Peugeottechnician with a Diag2000 computer can search through 6500 odddevices quickly - most problems can be diagnosed within 30 minutes.

According to Peugeot, 90% of malfunctions are resolved within a day.Cars can be updated with software to cure various problems quickly.

The system is still relatively new, and understandably is not yetperfect. However it is a good concept, and will improve in the future.For example, GPS and WAP technologies will be implemented in thenear future with voice activated telematics systems also on the menu.In Europe, a navigation system is already available.

Clever Multiplexed features

Intelligent Service Indicator - maintenance intervals aredetermined by the car's use, not just merely on a time or

mileage basis.

Automatic Lights & Wipers

Follow Me Home Lighting - lights illuminate for 45 seconds afterthe ignition is switched off (for automatic light equipped cars).

Automatic Boot Locking - when you drive over 10 km/h, theboot will lock to prevent robbers from stealing things from yourboot at traffic lights for instance.


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Emergency Braking Indicators - during emergency braking(deceleration at 8 m/s or greater), the indicators will turn on.

Automatic Window and Sunroof Closing - if you forget to closethese openings, the remote can close them for you after youlock the doors.

Equipment Security - Major 307 equipment is useless if stolen asit will only work in its original car. Multiplexing will also recordall breakin attempts.

More information can be found at the Peugeot Avenue website onMultiplex technology here

Automatic Transmission

Automatic gearboxes are finding favour all around the world, withabout 44% of cars worldwide using them. In Europe, according toRenault, this figure is 8% but expected to grow. In the US, 90% ofcars are already so equipped and in Japan almost 80% of cars have anautomatic transmission.

Automatic 307s are equipped with the latest version of the AL 4gearbox, which is also used in many other Peugeot models, includingthe N5 306, 206, 406 and 807. The AL4 was developed in conjunctionwith PSA partner Citroen, Siemens and Renault (DP0). PSA andRenault shared the development costs of 2.75 billion French francs(about 410 million USD) in 1997. It weighs 70kg, and can handle upto 330Nm of torque (210Nm on earlier versions). Hydraulic torqueconverter lock up is available on 2nd, 3rd and 4th gears. Transmission

oil is cooled by a heat exchanger. The Gearbox ECU uses 40 channels,which sends and receives information from the engine ECU via the CANnetwork. Peugeot claims the fuel consumption increase with thisgearbox over the manual equivalent is small - in the 307 1.6, there isonly a 0.2l increase for every 100km driven on the city cycle (AS2877).

In normal mode, the transmission is auto-adaptive, that is, it tries toshift according to your driving pattern. It considers the vehicle load,road gradient and surface, the speed of accelerator actuation andother factors such as gearbox oil temperature and enginetemperature. The computer creates an identikit portrait of the driver


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within a minute, considering the speed of the car, the number of timesand the speed at which the driver presses the accelerator (and itsposition). From this the computer categorieses the driver as being inan economical, sporting or medium category. These categoriescorrespond with a set of gearshift rules which favour either economy,performance or a compromise between the two, which is determinedfrom an average of values over the past few minutes. This can betemporarily changed if the accelerator is pressed rapidly - the ECU will

select the next sportier program (ie. from ECO to MEDIUM or MEDIUMto SPORT) - upon release, the transmission resumes the earlier mode.

Normal Mode Pattern Selection - Table

Vehicle Driving Conditions

Driving

ConditionsDownhill

Level

Ground

Average

Ascent

Steep

Ascent

ECO

Pattern

DESCENTPattern

ECO PatternBRAKINGPattern 1

BRAKINGPattern 2

MEDIUM

Pattern

DESCENTPattern

MEDIUMPattern

BRAKINGPattern 1

BRAKINGPattern 2

SPORT

Pattern

SPORTPattern

SPORTPattern

SPORTPattern

BRAKINGPattern 2

There are 6 'laws' from which the transmission can choose inauto-adaptive (normal) mode. ECO Pattern and BRAKING Pattern 1are the most common modes used. Two additional modes can also bemanually selected.

Sports mode automatically limits the transmission to the two mostdynamic/sporty/aggressive modes. In sports mode, the cars holds ontogears longer, will not shift into 4th gear until high speeds (ie.+100km/h) and shifts down eagerly to provide engine braking (bothunder brakes, and when slowing down without brakes). It is alsoslightly less eager to lock up the torque converter. Sports mode isvery effective for sporty driving, more so than most other automatictransmissions, as the torque converter is locked up, and hence enginebraking is also provided - which is noticeable under braking. Theaggressiveness of downshifting under braking depends on factors such

as the gradient and the amount of braking applied by the driver.

In Snow mode the car starts off in second gear, so as to reduce thelikelyhood of wheelspin. The transmission will have fewergearchanges, will not kickdown unless below 15 km/h, and will forcedownshifts on application of braking. This is the only mode notselected by the auto-adaptive system.

In addition to the aforementioned automatic modes, the AL 4 in the307 is also equipped with a Porsche Tiptronic system (manual mode).


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The driver can manually change gears (without clutch), by pushing thegearstick forward to upshift, and to downshift by pulling back on theshift lever. The system will not allow any potentially hazardous shiftsto take place - it will not allow a downshift if it will overrev the engine.Conversely, it will also upshift when engine revs are too high. Inaddition, when too high a gear is selected (eg. 4th gear at low speeds),the engine will either unlock the torque converter or downshift toprevent the engine from stalling. In total, the AL4 has 10 modes.

In the interests of safety, theoretically the transmission will not upshiftif the accelerator pedal is suddenly released. Peugeot claims it issealed for life, requiring no fluid changes. However, the transmissionhas an oil wear counter, allowing 6000 hours of operating at oiltemperatures below 95C (32,958 units of wear). Using Diag2000, atechnician can determine whether the fluid requires changing.

When the transmission is cold (


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for the wheels to lock, so that they can bite through the gravel.

The Bosch 5.3 ABS 4 channel/sensor system used in the 307 is muchmore sophisticated and refined than earlier ABS systems - modulationthrough the brake pedal during emergency braking is light. Theamount of modulations per second of braking is increased. Someearlier Peugeots used a Teves system.

EBFD. The Bosch EBFD was first introduced in the 406 back in 1998.Under normal circumstances, 60% of braking in a modern car isdirected to the front brakes. EBFD, through the ABS system's sensorsand electronic valves, allows braking to be adjusted between the frontand rear wheels (ie. to account for weight transfer during braking),and between the left and right rear wheel. This results in moreeffective braking, applying braking effort to the wheels with thegreatest grip.

How does this actually help you? During braking, the car's weight istransferred forward, so greater braking effort towards the front isprovided. When braking whilst cornering, a similar thing happens -weight is transferred from the inner wheel to the outer wheel, andbraking effort is directed to reflect this. So it optimises brakingbetween the front and the rear, and from left to right.

BAS/EBA. Electronic Brake Assist was launched on the 607. BrakeAssist System applies maximum braking effort during an emergencybraking situation to reduce stopping distance. Aside from fasterstopping, the effort required by the driver to brake the car is furtherreduced. At 100km/h, stopping distance can be reduced by anything

from 20% to 60%.

During slow braking, braking power is magnified by a factor of 6.Under emergency braking, EBA amplifies braking power by a factor of23.

For more information, see EBA at the Peugeot Avenue website here

When you consider these features, and the size of the 307's discbrakes (front 283mm, rear 247mm), it is no surprise that the 307 isone of the fastest stopping cars out there on the marketplace.

According to a test in NZ Autocar (JAN02), it was the fastest stoppingout of the VW Golf, Honda Civic and Toyota Corolla, stopping from 100km/h in 36.15m.

Steering

The 307 has a variable electro-hydraulic power steering system. Thehydraulic assistance is varied according to the speed of the car, andthe rate at which the steering wheel is turned. For instance, in anemergency manouvre, maximum assistance is provided.


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As electric power steering does not run directly off the engine, powerloss is reduced, and fuel consumption is improved.

The steering column is adjustable by 40mm in both height and reach.In a frontal impact, it can retract by 50mm, and this mechanism alsoprevents the brake pedal from moving rearwards, preventing leginjuries.

Suspension

At the front, the 307 has pseudo MacPherson struts and lowerwishbone members. The two rubber bushes on the wishbones aidsteering (front) and noise suspression (rear). The anti roll bar isindirectly linked to the front wheels.

At the rear, the 307 uses a semi-independent torsion beam axle withcoil springs replacing the torsion bar trailing arm system of the 306.Basically it is a U shaped beam with two trailing arms attached at theends, with the hollow anti-roll bar positioned inside the U beam -attaching direct to the trailing arms. A little advertised fact about thissystem is that it retains the passive rear wheel steering system used inrecent Peugeots - but of a newer design. Centrifugal forces act on themetalastic controlled rubber bushes causing the rear suspension crossmember to move, turning the rear wheels. The steering angle isdependent on the level of force exerted.

The 307's suspension is quite compact, reflected in the roomy, wellshaped, intrusion free boot. The very common torsion beam

suspension is light, compact and cheap to make.


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Acoustic Comfort

In many parts of the 307's structure, explandable foam is used toreduce noise, as well as fusible plates (IFF). Mastic piping contributesto lower noise by improving the car's airtightness.

There is considerable insulation between the engine compartment andcabin to create a quiet cabin atmosphere.

Body

The 307's structure meets all requirements of EuroNCAP safety testing,and European repairability requirements for impacts below 15 km/h. Itutilises various materials, including much HLE - High Elastic Limit steelespecially in structurally significant support areas and joined sheets.

Various engine components such as the battery, brake assist amplifier(mastervac) and air filter are located in the engine bay to assist withthe absorbtion of crash energy. Shock absorbers are mounted onshafts incorporated into the front crumple zone to further absorb crashenergies, which can absorb 6000J of energy. The shafts can handle 9tonnes.

To reduce weight, the bonnet is made from aluminium, the frontfenders are made from a composite and the bumpers (Noryl), lightsand grille are made from plastic.

Glass

The 307 is equipped with athermic glass on the front and rearwindshields. A thin layer of metallic oxides is within the glass,reflecting solar rays, and hence reducing the level of heat energywithin the car. Light transmission is not particularly affected -however, from certain angles, you can see the thin layer of metalwithin the glass. The windshield sweeps back at 75.

This feature is especially useful in the 307, which has one of thelargest windshields of any passenger car - 1.46m2. By reducing theheat energy transferred into the cabin, less airconditioning is required,saving fuel and improving comfort.


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Airbags

The 307 is equipped with 6 airbags, a driver's airbag, passengerairbag, two side airbags located in the side of the front seats, and twocurtain airbags on both sides of the car. The system is intelligent,tailoring the airbag activation according to the nature of the impact.

For instance, one or two airbag gas generators can be activated,depending on the nature of the impact. Most cars only have onegenerator, unlike the 307's dual system.

Front airbags protect the torso and head during a frontal impact,whereas the curtain airbag and side airbags protect the head and torsorespectively in a side impact.

SCS - Spinal Care Technology

In addition to the side airbags located in the sides of the frontbackrests, the 307's seats are equipped with SCS technology. In theevent of a rear impact, the upper part of the seat and headrest bend


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forward 50 mm to cushion the body, reducing the potential for spinaldamage or whiplash. An anti collapse system prevents the headrestfrom retracting. The system is activated by pressure on the backrest.

Seat belts have a force limiting feature to reduce bruising in the eventof an accident.

In left hand drive (LHD) markets, an active footrest for the driver is

standard, reducing injuries to legs and feet. However RHD markets donot have this feature, and have no footrest at all.

Source: Peugeot Avenue website, PAA, PCCV Torque, other associatedPeugeot publications and various websites. I would like to especiallythank Peugeot Automobiles Australia for supplying me with extrainformation. All images on this page are Copyright AutomobilesPeugeot.

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MeganeAutomaticTransmission[1]